The in vitro biologic activity and in vivo efficacy of Hu23F2G in a nonhuman primate model of Experimental Allergic Encephamyelitis (EAE) support a potetial application in the treatment of MS. The acute exacerbation component of MS will be studied under this protocol. The rationale is that the EAE model is associated with acute onset of neurologic deficits and new lesions in the CNS, events that are analogous to the acute MS exacerbation.